Trim panel having integral door cover

ABSTRACT

An instrument panel has an integral door cover for concealing a supplemental inflatable restraint system in a vehicle passenger compartment. The door cover includes a flap that is an integral part of a flexible plastic skin of the instrument panel. The plastic skin is cast in a special mold with a raised apexed rib that forms grooves outlining the flap that have a thin tear seam at their bottom.

BACKGROUND OF THE INVENTION

This invention relates generally to supplemental inflatable restraintsystems often referred to as airbag systems. More particularly, thisinvention relates to a trim panel such as an instrument panel, having anintegral door cover for concealing the airbag system in a vehiclepassenger compartment.

SUMMARY OF THE INVENTION

U.S. Pat. No. 5,131,678 granted to John A. Gardner, Richard D. Rhodes,Jr. and Everett Hastings Jul. 21, 1992 discloses an air bag door coverthat is an integral part of a decorative panel for a steering wheel. Thepanel comprises an aluminum backing plate, an outer flexible vinyl skinarid an intermediate elastomeric urethane foam layer. The vinyl skin iscast with a rectangular groove that defines a door. The cast vinyl skinis then placed in a mold in a spaced relationship with the backing plateafter which the intermediate layer is foamed in place. The bottom of therectangular groove is then cut at least part way through on three sidesto provide a weakened section in the panel that includes an U-shaped cutline in the backing plate.

While the decorative panel of the above patent is well suited for itsintended purpose, it has a drawback in that the bottom of the groove iscut at least part way through on three sides after the vinyl skin iscast and assembled into the decorative panel. This cutting in turnrequires deep and narrow grooves to hide the cut. These grooves limitaesthetic design choices and may be difficult to form.

The object of this invention is to provide a trim panel that has anintegral door cover for an airbag system that does not require cuttingthe bottom of the grooves.

Another object of this invention is to provide a trim panel that has ashaped plastic skin that includes a flap for an integral door cover fora SIR system that is partially outlined by a groove that does notrequire any cutting after the skin is cast to provide a weakened tearseam.

Still another object of this invention is to provide a trim panel thathas an integral door cover for an airbag system that includes a shapedplastic skin having a flap partially outlined by a groove that is castin an aesthetically pleasing manner to include a weakened tear seam atits bottom that does not require any cutting after the skin is cast.

Still yet another object of this invention is to provide a method formaking such a trim panel and a mold for use in practicing the method.

A feature and advantage of the trim panel of this invention is that thetrim panel has a cast plastic skin which includes a flap for an integraldoor cover that is cast in a special mold that produces a weakened tearseam in the bottom of an aesthetically pleasing groove that does notrequire any cutting after the skin is cast.

Still another feature and advantage of the invention is that trim panelis cast in a mold that has a raised rib for forming a groove thatpartially outlines a flap in a cast plastic skin and that includes atear seam that can be ruptured by a deploying airbag without any needfor cutting the tear seam after the plastic skin is cast.

Yet still another feature and advantage of the invention is that itprovides a special mold having a uniquely shaped rib for casting aflexible plastic skin so that the cast plastic skin is formed with agroove that partially outlines a flap and that includes a tear seam thatcan be ruptured by a deploying air bag without any need for cutting thegroove.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the inventionwill become more apparent from the following description taken inconjunction with the accompanying drawings wherein like references referto like parts and wherein:

FIG. 1 is a perspective view of an automotive instrument panel thatincludes an integral door cover made in accordance with this invention;

FIG. 2 is a fragmentary sectional view of a first embodiment of theinvention taken substantially along the line 2—2 of FIG. 1 looking inthe direction of the arrows;

FIG. 3 is a fragmentary perspective view of a special mold for making acast skin for the automotive instrument panel of FIG. 1 that is made inaccordance with this invention;

FIG. 4 is a section of the mold taken substantially along the line 4—4of FIG. 3 looking in the direction of the arrows;

FIG. 5 is a fragmentary perspective view of the mold of FIG. 3 showingthe skin cast in place on the mold;

FIG. 6 is a section taken substantially along the line 6—6 of FIG. 5looking in the direction of the arrows;

FIG. 7 is a section of an alternative mold for making a cast skin for analternative automotive instrument panel that is made in accordance withthis invention and showing the skin cast in place on the mold inphantom;

FIG. 8 is an enlarged fragmentary sectional view similar to FIG. 2showing the cast skin of FIG. 7 incorporated in the alternativeautomotive instrument panel;

FIG. 9 is an enlarged fragmentary sectional view similar to FIG. 2showing another alternative automotive instrument panel.

DESCRIPTION OF THE INVENTION

Referring now to the drawing, FIG. 1 shows an instrument panel 10 havingan airbag system 12 located beneath an integral door cover 14constructed in accordance with this invention. In this particularinstance, the airbag restraint system 12 is located beneath the top ofthe instrument panel on the passenger side of the vehicle. However theintegrated door cover of this invention can be used on the driver sideas part of a trim panel for the steering wheel; on either side as partof the front or facing portion of the instrument panel; or as part ofany other trim panel that is strategically positioned in the passengercompartment.

The airbag system 12 includes an airbag housing 16 that encloses a gasgenerator 18 for supplying an inflatant to an airbag 20 that iscollapsed, folded and packed in the housing 16. The folded airbag 20includes an inlet end 22 connected to a passage for flow of theinflatant from the gas generator 18 into the airbag. The airbag alsoincludes a nose end 24 at the opposite end of the folds that ispositioned to open the door 14 when the airbag 20 inflates.

The instrument panel 10 comprises a substrate or support 30 ofstructural plastic material such as ABS/Polycarbonate, Polypropylene,Polyphylene Oxide (PPO)/HIPS or Styrene Malaeic Anhydrid (SMA). Thesubstrate 30 has a rectangular opening for deployment of the air bag 20that is closed by a door back plate or reinforcement 32 of aluminum orother light weight metal. The door back plate 32 is connected to thesubstrate 30 by a hinge 33 at a back end. The opposite or front end ofthe door back plate 32 is supported on a depressed lip 34 of thesubstrate 30 at the front edge of the rectangular opening for the door14 when the door 14 is in the closed position as shown in FIG. 2.

The airbag housing 16 is supported beneath the door 14 by a dependingrectangular plastic bracket that is welded or otherwise suitably securedto the bottom of the substrate 30.

The outer surface of the substrate 30 and the hinged door back plate 32is bonded to a layer of a suitable energy absorbing elastomeric foam,such as urethane foam that forms a cushion 38 in an underlyingrelationship to a polymeric skin or shell 40 of vinyl or other suitableflexible plastic material such as thermoplastic urethane (TPU),thermoplastic olefin (TPO) or polyester that forms an outer decorativesurface of the instrument panel 10.

The skin 40 has three grooves 42 in a U-shaped pattern that outline aflap 44 that is aligned with front and side edges of the hinged doorback plate 32. The grooves 42 are formed to provide tear lines orweakened sections for separating the skin flap 44 as explained below.The grooves 42 are also formed so that there are not any cuts needed inthe bottom of the grooves. Consequently, the uncut grooves 42 alsoimprove the aesthetic appearance of the instrument panel 10 as explainedbelow.

Referring now to FIGS. 3 through 6, the polymeric skin 40 may be madefor example by a drysol casting process such as that disclosed in U.S.Pat. Nos. 4,562,025 and 4,610,620 granted to John D. Gray Dec. 31, 1985and Sep. 9, 1986 respectively. These patents are hereby incorporated inthis patent specification by reference. Other examples of processes ormethods for shaping the polymeric skin include rotational casting,liquid casting, blow molding and vacuum forming. In any event, the vinylskin 40 is cast using a special mold 100 that produces the three grooves42 in the U-shaped pattern that defines the skin flap 44 for the doorcover 14 that opens when the airbag 20 is deployed.

FIG. 4 shows a portion of the special mold 100 for casting the vinylskin 40 which is preferably cast using a drysol casting process such asthat described in the two U.S. Patents that are identified above andthat are incorporated in this patent specification by reference. Moreparticularly, FIG. 4 shows the portion of the mold 100 for casting theportion of the vinyl skin 40 that includes the integral flap 44. Thisportion of the mold 100 has a raised narrow rib 102 in a U-shapedpattern. The top of the narrow rib 102 is slanted to provide a V-likeapex 104 as shown in FIG. 4. When the skin 40 is cast in the mold 100 ina drysol casting operation, the casting material thins out over the topof the raised narrow rib 102 of the mold 100 and a very thin section isformed at the apex 104 of the rib 102. FIGS. 5 and 6 show a fragmentaryportion of the vinyl skin 40 after it has been cast in the mold 100. Thecast vinyl skin 40 has a depending portion 41 in a U-shaped pattern thatis formed by the raised rib 102 of the mold 100 and that contains thegroove 42. The groove 42 has a bottom which includes a very thin section43 that forms over the apex 104 of the raised rib 102 as shown in FIG.6. The thin section 43 is considerably thinner than the rest of the castskin 40 and can have a thickness that is as little as 25% of thepredominate or nominal thickness of the cast skin 40.

This thin section provides a tear seam in the bottom of the groove 42without any need for cutting after the skin 40 is cast. Since there isno need to hide the bottom of the groove 42, the groove may berelatively shallow as shown in FIG. 2 where the depth to width ratio isabout 2 to 1. The possibility of shallower grooves provides the designerwith a wider range for style lines and the manufacturer with an easiermanufacturing job.

A general criterion for a tear seam is that the tear seam should have atensile strength of no more than about 50% of the tensile strength ofthe rest of the skin. Consequently, a suitable tear seam can be providedwith a thin section at the bottom of the groove 42 that has a thicknessthat is as much as about 50% of that of the rest of the skin. Of coursethe precise thickness required will vary somewhat with the skin materialselected and customer requirements for the tensile strength of the tearseam. However, the formulation of the selected skin material and theshape of the groove 42 and the raised rib 102 can be varied to producethe desired thickness of the tear seam by the thinning of the skinmaterial on the raised rib 102 during the casting process.

To manufacture instrument panel 10, the vinyl skin 40 with the flap 44outlined by the groove 42 shown in FIGS. 5 and 6 is demolded and placedin the cavity of a conventional closeable mold that has a cavity that isshaped to correspond to the desired shape of the instrument panel 10.The substrate 30 and hinged door reinforcement 32 are then placed in aspaced relationship in the closed mold and the intermediate elastomericlayer 38 is then foamed in place in a conventional manner to provide theinstrument panel 10 that is partially shown in section in FIG. 2.

Referring now to FIGS. 7 and 8, FIG. 7 shows a section of an alternativemold 200 for making a cast skin 240 for an alternative automotiveinstrument panel 210 that is partially shown in FIG. 8 and that is alsomade in accordance with this invention. More particularly, FIG. 7 showsthe section of the mold 200 for casting the portion of the vinyl skin240 that contains a U-shaped groove 242 that outlines an integral flap244 of the door cover 214. This portion of the mold 200 has a raisednarrow rib 202 in a U-shaped pattern. The narrow rib 202 has concaveside walls to provide a cusp-like apex 204 at the top of the rib 202.When the skin 240 is cast in the mold 200 in a drysol casting operation,the casting material progressively thins out over raised narrow rib 202of the mold 200 and a very thin section is formed at the cusp-like apex204 of the rib 202. FIG. 7 shows a fragmentary portion of the vinyl skin240 in phantom after it has been cast in the mold 200. The cast vinylskin 240 has a depending portion 241 in a U-shaped pattern that isformed by the raised rib 202 of the tool 200 and that contains thegroove 242. The groove 242 has a bottom which includes a very thinsection 243 that forms over the cusp-like apex 204 of the raised rib 202as shown in FIG. 7.

To manufacture instrument panel 210, the vinyl skin 240 with the flap244 outlined by the groove 242 shown in FIG. 7 is demolded and placed inthe cavity of a conventional closeable mold that has a cavity that isshaped to correspond to the desired shape of the instrument panel 210.The substrate 230 and hinged door reinforcement 232 are then placed in aspaced relationship in the closed mold and the intermediate elastomericlayer 238 is then foamed in place in a conventional manner to providethe instrument panel 210 that is partially shown in section in FIG. 8.The groove 242 is in the nature of a “gull wing” shaped style line thatis formed with a converging gap between rounded edges 246 of theintegral flap and adjacent rounded edges 248 of the vinyl skin 240 atthe surface of the instrument panel 210. However, the groove 242 isstill formed with a very thin section 243 at the bottom that provides atear line or weakened section for separating the flap 244 thateliminates any need for cutting the skin 240 after it is cast. Thus theinvention provides a wide range of aesthetic alternatives for thedesigner.

Aside from the differences noted above, the instrument panel 210 isotherwise the same as the instrument panel 10 and corresponding partsare identified by adding 200 to the identifying numerals for the partsof instrument panel 10.

Another alternative instrument panel 310 is shown in FIG. 9. Thisinstrument panel 310 is characterized by a groove 342 that provides awider “gull wing” style line that outlines the flap 344 of the doorcover 314 in the skin 340. The skin 340 is cast in a mold similar tothat shown in FIG. 7 so that the depending portion 341 of the skin 340that defines the groove 342 progressively thins out to a very thinsection 343 at the bottom that provides a weakened section or tear linewithout any need for cutting. The substrate 330 also does not have asupport lip for the front end of the door back plate 332 which ischaracteristic of small doors or dual door arrangements. The instrumentpanel 310 is otherwise the same as the instrument panel 210.

An advantage of these “gull wing” style lines is that they are generallyregarded as more aesthetically pleasing and easier to tool.

All of the foregoing instrument panels operate in the same manner. Whenthe gas generator 18 is triggered due to a predetermined vehicledeceleration, the airbag 20 inflates at the nose end 24 first and thenprogressively back toward the inlet end 22. Consequently the nose end 24engages the metal door reinforcement 32, 232 or 332 and pivots itoutwardly about hinge 32. As the door pivots outwardly, the foam layer38, 238 or 338 and then the skin 40, 240 or 340 is fractured at theweakened sections or tear lines to create a separated flap 44, 244 or344 and an opening for deployment of the airbag 20 that corresponds withthe rectangular opening in the substrate 30, 230 or 330.

While a U-shaped pattern of three grooves has been described forpurposes of illustration, other arrangements are possible. For instance,four grooves or an H-shaped or X-shaped pattern may be used. In otherwords, the invention has been described in an illustrative manner, andit is to be understood that the terminology which has been used isintended to be in the nature of words of description rather than oflimitation.

Obviously, many modifications and variations of the present invention inlight of the above teachings may be made. It is, therefore, to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A trim panel having adoor cover for concealing an airbag system in a vehicle passengercompartment and a flexible plastic skin that includes a flap that is anintegral part of the door cover comprising: the flexible plastic skinhaving a depending portion that contains a groove for providing a tearseam between the flap and the remaining part of the polymeric skin, alayer of energy absorbing elastomeric foam underlying the plastic skin,and the groove being formed so that it has a weakened section in thelayer of energy absorbing elastomeric foam that can be fractured bydeployment of an airbag without any need for cutting the groove.
 2. Thetrim panel as defined in claim 1 wherein the flexible plastic skin iscast in a mold having a raised rib that forms the groove so that it hasa thinner section at its bottom.
 3. The trim panel as defined in claim 2wherein the flexible plastic skin is cast in a mold having a raised ribthat forms the groove so that the groove is gull wing shaped.
 4. Thetrim panel as defined in claim 1 wherein the flexible plastic skin iscast in a mold with a raised rib so that the groove has a bottom thatincludes a thin section that provides a tear seam that can be fracturedby deployment of an air bag without any need for cutting the plasticskin after it is cast.
 5. The trim panel as defined in claim 1 whereinthe thin section has a thickness that is in the range of about 25% to50% of the nominal thickness of the remainder of the skin.
 6. A methodfor making a trim panel having a door cover for concealing an airbagsystem in a vehicle passenger compartment and a flexible plastic skinthat includes a flap that is an integral part of the door covercomprising: casting a flexible plastic skin in a mold that has a raisedrib so that the skin has a depending portion that contains a groove thatconforms to the shape of the raised rib, and the raised rib having a topthat has an apex so that the groove is formed with a bottom that is castwith a thin section that forms over the apex to provide a tear seam forthe skin flap that can be fractured by deployment of an airbag withoutany need for cutting the bottom of the groove.
 7. The method for makinga trim panel as defined in claim 6 further comprising: placing the castskin in a closeable mold, and foaming an elastomeric layer in placebeneath the polymeric skin so that the depending portion is disposed inthe layer generated in the foaming process.
 8. The method for making atrim panel as defined in claim 6 wherein the top of the raised rib has aV-like apex.
 9. The method for making a trim panel as defined in claim 6wherein the raised rib has concave sides that provide a cusp-like apexat the top of the raised rib.
 10. A mold for casting a flexible plasticskin for a trim panel having a door cover for concealing an airbagsystem in a vehicle passenger compartment wherein the flexible plasticskin includes a flap that is an integral part of the door cover, themold comprising: a raised rib that forms a depending portion in theflexible plastic skin that contains a groove that conforms to the shapeof the raised rib when the flexible plastic skin is cast in the mold,and the raised rib having a top that has an apex so that the groove isformed with a bottom that is cast with a thin section that forms overthe apex to provide a tear seam for the flap that can be fractured bydeployment of an airbag without any need for cutting the bottom of thegroove.
 11. The mold for making a trim panel as defined in claim 10wherein the raised rib has a height to width ratio of about 2 to
 1. 12.The mold for making a trim panel as defined in claim 10 wherein the topof the raised rib has a V-like apex.
 13. The mold for making a trimpanel as defined in claim 10 wherein the raised rib has concave sidesthat provide a cusp-like apex at the top of the raised rib.
 14. A methodfor making a trim panel having a door cover for concealing an airbagsystem in a vehicle passenger compartment and a flexible plastic skinthat includes a flap that is an integral part of the door covercomprising: casting a flexible plastic skin in a mold that has a raisedrib so that the skin contains a groove that conforms to the shape of theraised rib, the raised rib having a top so that the groove is formedwith a bottom with a thin section to provide a tear seam for the skinflap that can be fractured by deployment of an airbag without any needfor weakening the bottom of the groove; placing the cast skin in aclosable mold; and foaming an elastomeric layer in place beneath theplastic skin.
 15. A method for making a trim panel having a door coverfor concealing an airbag system in a vehicle passenger compartment and aflexible plastic skin that includes a flap that is an integral part ofthe door cover comprising: forming a flexible plastic skin in a moldthat has a raised rib so that the skin contains a groove that conformsto the shape of the raised rib, the raised rib having a top so that thegroove is formed with a bottom with a thin section to provide a tearseam for the skin flap that can be fractured by deployment of an airbagwithout any need for weakening the bottom of the groove; and forming afoam layer beneath the plastic skin.